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Re: [Qemu-block] [PATCH RFC 0/7] COLO block replication supports shared
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-block] [PATCH RFC 0/7] COLO block replication supports shared disk case |
Date: |
Tue, 22 Nov 2016 10:33:40 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Thu, Oct 20, 2016 at 09:57:33PM +0800, zhanghailiang wrote:
> COLO block replication doesn't support the shared disk case,
> Here we try to implement it.
>
> Just as the scenario of non-shared disk block replication,
> we are going to implement block replication from many basic
> blocks that are already in QEMU.
> The architecture is:
>
> virtio-blk ||
> .----------
> / || |
> Secondary
> / ||
> '----------
> / ||
> virtio-blk
> / ||
> |
> | ||
> replication(5)
> | NBD --------> NBD (2)
> |
> | client || server ---> hidden disk <--
> active disk(4)
> | ^ || |
> | replication(1) || |
> | | || |
> | +-----------------' || |
> (3) |drive-backup sync=none || |
> --------. | +-----------------+ || |
> Primary | | | || backing |
> --------' | | || |
> V | |
> +-------------------------------------------+ |
> | shared disk | <----------+
> +-------------------------------------------+
> 1) Primary writes will read original data and forward it to Secondary
> QEMU.
> 2) The hidden-disk will buffers the original content that is modified
> by the primary VM. It should also be an empty disk, and
> the driver supports bdrv_make_empty() and backing file.
> 3) Primary write requests will be written to Shared disk.
> 4) Secondary write requests will be buffered in the active disk and it
> will overwrite the existing sector content in the buffe
This design looks good. I have not reviewed the patches in detail but
will review the next revision.
Stefan
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- Re: [Qemu-block] [PATCH RFC 0/7] COLO block replication supports shared disk case,
Stefan Hajnoczi <=